Arteriovenous malformation - cerebral

Definition

A cerebral arteriovenous malformation is an abnormal connection between the arteries and veins in the brain that usually forms before birth.

Alternative Names

AVM - cerebral

Causes

The cause of cerebral arteriovenous malformation (AVM) is unknown. The condition occurs when arteries in the brain connect directly to nearby veins without having the normal vessels (capillaries) between them.

Arteriovenous malformations vary in size and location in the brain.

An AVM rupture occurs because of pressure and damage to brain tissue, as well as a lack of blood flow to the brain. Symptoms may also occur when large AVMs that have not bled press on the brain tissue.

Cerebral arteriovenous malformations occur in less than 1% of people. Although the condition is present at birth, symptoms may occur at any age. Hemorrhages occur most often in people ages 15 - 20, but can also occur later in life. Some patients with an AVM also have cerebral aneurysms.

There are often no symptoms until the AVM ruptures. This results in sudden bleeding in the brain (hemorrhagic stroke). In more than half of patients with AVM, hemorrhage is the first symptom. Symptoms of AVM hemorrhage are the same as those of other intracerebral hemorrhage.

Signs and tests

A complete physical examination and neurologic examination are needed, but they may be completely normal.

Open brain surgery removes the malformation through an opening made in the skull. It must be done by a highly skilled neurosurgeon.

Embolization (endovascular treatment) is the injection of a glue-like substance into the abnormal vessels to stop blood flow in the AVM and reduce the risk of bleeding. This may be the first choice for some kinds of AVMs, or if surgery cannot be done.

Stereotactic radiosurgery is another alternative. This procedure delivers radiation directly to the area of the AVM to cause scarring and shrinkinge. It can control bleeding and other symptoms. It is particularly useful for small deep AVMs, which are difficult to remove by surgery.

Anti-convulsant medications, such as phenytoin, are usually prescribed if seizures occur.

Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Daniel B. Hoch, PhD, MD, Assistant Professor of Neurology, Harvard Medical School, Department of Neurology, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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